Abstract
This paper will discuss the hearing condition known as tinnitus and examine the drugs and nutrients that could potentially shed light on statistically reliable treatments in the future. First, a short history of the condition itself will be presented, followed by a brief description of each of the chemical treatments that have claimed success in treating or suppressing tinnitus symptoms. Finally, an overview of ways to prevent tinnitus from occurring will be discussed.
Introduction
Tinnitus is the perception of sound, usually a ringing noise, within the human ear in the absence of corresponding external stimuli. It is a fairly common condition, particularly in the age group of 55 and 65 years old. Although a wide range of causes for tinnitus exists, the most common is noise-induced hearing loss. This is particularly problematic in recent times, as many of today’s youth and young adults unknowingly subject themselves to damaging levels of noise, particularly music, through the invention of speakers that amplify noise and headphones that deliver sound directly into the ear canal without any means for the sound to be lowered in decibel level through absorption of the surroundings. These ease with which this condition occurs, along with the difficulty in circumventing the subjective nature of this condition makes it important to discover a full-proof method of treating tinnitus, as well as how to avoid getting it in the first place. [1]
History of Tinnitus
Tinnitus is a condition that can affect the outer, middle, and inner ear of one or both ears. It is the perception of auditory stimuli not produced externally to the ear. The exactly noise perceived can vary in pitch (high to low), tone (single or multi-tonal), and frequency (constant, pulsing, or intermittent). Tinnitus is not a disease or disorder, but a condition that can result from a wide range of underlying causes: neurological damage (such as multiple sclerosis), ear infections, oxidative stress, muscle spasms, wax build-up in the ear canal, sensoineural hearing loss, congenital hearing loss, and exposure to loud sounds. Noise-induced hearing loss is the most common, resulting from excessively loud sounds, firearms, and music. [1]
The condition is rated clinically according to the practical difficulties it imposes on the patient, such as interference with sleep, quiet activities (particularly those that require concentration), and normal daily activities, causing withdrawal or depression. Tinnitus can be classified as objective, where the perceived noise is something produced inside the ear such as muscle spams that is audible to the physician, and subjective, where the noise is audible only to the patient. Subjective tinnitus, the far more common form that accounts for 95% of tinnitus cases, is a symptom that is associated with practically every known ear disorder. [1]
Tinnitus has been eluding health care professionals for quite some time. As a usually subjective phenomenon, it is difficult to measure using objective tests, such as by audiometric test, where the perceived noise is compared with noise of known frequency and intensity. Because tinnitus is subjective, two individuals may demonstrate identical tinnitus loudness and pitch matches yet be affected in significantly different ways. The severity of the tinnitus is largely a function of the individual's reaction to the condition. [1]
Alterations to the balance of excitatory and inhibitory inputs of neurons in the auditory system are believed to cause tinnitus. High-intensity noises that cause hearing loss damage auditory receptions in the inner ear, resulting in hearing loss that alters neuronal activity in the auditory system of the brain, causing tinnitus. Several areas of the brain show signs of tinnitus activity; this is most notable in the dorsal cochlear nucleus where direct input is received from the auditory nerve. Loss of auditory nerve function results in high rates neural activity in the absence of stimuli. The brain then perceives the increased neural activity as sound, particularly high frequency sound such as the ringing perceived by tinnitus patients. The inferior colliculus, which receives input from the cochlear nucleus, increases in spontaneous neural activity as a result. [2], [3] The dorsal nuclear cochlear nucleus is considered the primary source of tinnitus activity, as its role in sound localization and inhibition of noises in hearing, in addition to its ability to be influenced by attentional and emotional impulses sent from the brain, makes it highly compatible with the symptoms resulting from tinnitus. [3]
The auditory cortex is also affected, causing neural impulses to synchronize so that impulses occur simultaneously, amplifying tinnitus. Damage to the ear from noise exposure distorts frequency perception such that the brain becomes insensitive to sound frequencies of the range of hearing loss. Neurons whose input frequency have been lost alter to become sensitive to noises at the edge of the lost frequency, resulting in an expansion of the representation of frequencies near that of the hearing loss at the cost of equal representation of the entire range of audible frequencies. This could possibly affect tinnitus. [2], [3]
Hearing loss throws off the balance between excitatory synapses which increase neural activity and inhibitory synapses that reduce neural activity. Excitation is necessary for delivering responses to stimuli throughout the brain and enhancing important signals, while inhibition is necessary for turning off response to stimuli to avoid an information overload to the brain. Hearing loss results in a decrease of auditory inhibition, coupled with an increase in excitatory synaptic response. Decrease in inhibitory synapses could thus be responsible for the inability of many tinnitus patients to filter out the tinnitus ringing for other sounds. In addition, increased levels of acetylcholine have been noted to occur after hearing loss. This could be the brain’s mechanism to boost its ability to perceiving incoming signals. The resulting amplification allows the neural signals caused by hearing loss to be more easily perceived, thus resulting in tinnitus. [2]
Tinnitus plays on the consciousness of the patient based on the intensity of its frequency, with fairly light tinnitus merely reduced to an annoying background noise while debilitating tinnitus consuming the attention of the patient. It is thought that those whose tinnitus falls into a lower level of consciousness may possess cortical deafness that prevents the person from deciphering or associating sounds despite being able to perceive them, which in turn keeps the tinnitus from rising high enough in the hierarchy of awareness to pose a notable issue. Those with remaining function in the auditory cortex suffer from more acute tinnitus due the piercing quality of the noise, which is perceived by the limbic cortex as a disturbance. This causes a negative association to the sound. [2]
The attention to the noise produced by tinnitus can also be traced back to the dorsal cochlear nucleus, inferior colliculi, and the brainstem, as evidenced by cats’ ability to discern noises of varying intensities arriving at the two ears at different times, which requires attention. Changes in the activity of the dorsal cochlear nucleus in animals when they shift their attention between auditory and non-auditory stimuli suggest the dorsal cochlear nucleus’ role in attention. In addition, it has been shown that the dorsal cochlear nucleus and inferior colliculi function in attention regulation. Testing with hydranencephaly sufferers who lack of cerebral hemispheres but maintain an intact brainstem has shown these individuals to show interest to certain sounds and respond emotionally to them. This suggests that these low-level auditory centers might serve to enable the brain to focus on specific details in the sensory world and while ignoring those deemed irrelevant. [2], [3]
Auditory Treaments
Current research suggests that even though tinnitus may initially be caused by an injury to the ear, ultimately an auditory pattern is established in the brain. Therefore, many treatment approaches are directed at the brain, not the ear. [2], [3] Other treatments reduce or mask the noise, making tinnitus less noticeable. It has been theorized that hearing can be restored by reversing the plasticity changes made by hearing loss through restoration of sound stimulation to the areas of the brain that have lost input. This restored plasticity should reduce activity that causes tinnitus. In a series of studies, cats were exposed to loud noises to induce hearing loss. All the changes to auditory responses in the brain, such as the increases neural plasticity, synaptic changes, and the others detailed above were found to have occurred in the cats. These same cats were then exposed to auditory stimulation in the frequency range of hearing loss and were found to have greatly restored the balance of synapses and reduced the activity of neurons and their synchronization. This greatly supports the idea that acoustic therapies could be a potent treatment for hearing loss and tinnitus symptoms. [2]
Related to audio therapies, many tinnitus victims are encouraged to use white noise therapy. White noise is a combination of all the frequencies of sound, equally distributed across the audio band. Simply put, it is an artificially produced noise that is steady and unvarying in quality and unobtrusive to the listener. This gives it the quality of “background noise” that people tend to find soothing. Tinnitus patients utilize headphones or speakers to transmit the white noise and help to cover up the sound of tinnitus while conditioning the brain to place the tinnitus sounds at a position of lower attention. Although it is generally agreed that white noise therapy is incapable of curing tinnitus, it is quite useful for masking the noise, particularly during sleep where tinnitus is most noticeable. In addition to masking the ringing, white noise therapy has been found to be highly therapeutic for many people. The calming effect is useful for dealing with the emotional and attentional factors that plague many tinnitus patients. [4]
Natural Treaments
The safest and most natural remedies for tinnitus are those that occur within the human body naturally. Melatonin is a naturally occurring chemical compound with a host of uses in the human body, as well as animals and plants. It functions as a regulator in the circadian rhythm, an antioxidant that can easily cross cell membranes and the blood-brain barrier, a participant in the immune system (though the degree to which it serves is thus far unclear), and an anti-aging agent. [5]
Because of its role in the regulation of the circadian rhythm, which includes the sleeping cycle, melatonin has been investigated as a possible alleviation for tinnitus patients with resulting sleep disorders. Multiple sources have tested this by prescribing a certain amount of melatonin to patients and observing their sleep over a period of several weeks. All the studies agreed that there exists an association between the amount of improvement in sleep and tinnitus intensity and the added supplementation of melatonin. The melatonin treatment had the greatest impact among patients with the worst sleep quality, but not necessarily the most severe tinnitus in all studies. Interestingly, most reported that those most affected were men, and whose tinnitus appeared to be the result of exposure to high intensity noises. [5]
Another possible treatment is zinc supplementation. Zinc, an essential trace element present in all organs, tissues, fluids, and secretions of the body, is widely distributed in the central nervous system, including the auditory pathway and the cochlea. Some studies have shown that hypozincemia, a deficiency in zinc, could cause tinnitus in patients with relatively normal hearing or exacerbate tinnitus symptoms in others. From these studies, it has been concluded that clinical and subjective improvement of tinnitus can be achieves by supplementation with oral zinc medication. Although the extent to which zinc supplements are capable of treating tinnitus in the long run has not been studied with large groups, its smaller scale success indicates that it is well worth looking into. [6], [7], [8]
Antidepressant Treaments
There exist more controversial treatments, most revolving around antidepressant drugs. Many physicians prescribe benzodiazepines to patients suffering from tinnitus. Benzodiazepines are a group of drugs that affect brain function to alter perception, mood, cognition, and behavior (psychoactive drugs). It has a host of uses in the medical community for its sedative, hypnotic, anxiolytic, anticonvulsant, and muscle relaxant properties, which are useful in a variety of indications such as alcohol dependence, seizures, anxiety, panic, agitation and insomnia. In some cases, it has been said to help alleviate the symptoms of tinnitus, as well as the depression that often accompanies it. [9] However, benzodiazepines carry a stigma for their host of adverse affects, particularly their withdrawal and long term effects that can cause physical and mental deterioration in the patient. Tricyclics, a wide variety of drugs that can function as antidepressants, antipsychotics, or antihistamines have shown some capacity to treat tinnitus, usually where depression is involved. Amitroptyline has been shown to provide some relief for tinnitus, particularly in those whose tinnitus is exacerbated by emotional states. [10] In some studies to have a high percentage rate of success among those suffering from tinnitus, as high as 95%. [11] However, in many other studies, the results are far less enthusiastic. In some cases, the success rate with the amitroptyline was roughly equivalent to the placebo group and thus insignificant in treating the tinnitus; in others, the effects grew worse with increased amount of the tricyclic. [12], [13]
However, one drug that has shown potential is acamprosate, a drug that stabilizes the chemical balance of the brain. This is usually used to treat alcohol dependence, but has shown promising capacity for treating tinnitus and carries far fewer and less acute symptoms than benzodiazepines or tricyclics. It is believed that acamprosate may improve tinnitus by acting on the ear and the nervous system by means of glutamate antagonist and GABA agonist action. [14] In the studies performed it had a very high rate of success in relieving tinnitus symptoms, with many patients claiming that it had relieved tinnitus up to 50%. In all, acamprosate has been considered a safe and alternative treatment for tinnitus, particularly of sensorineural origin. [14], [15]
Although the disadvantages of drug like antidepressants may make their suitability as tinnitus treatments suspect, the questions that have arisen from the studies involved with these drugs have brought a new angle on tinnitus to light. The nature of tinnitus may be such that much of its effects are rooted deep in the mind. Factors like stress, blood pressure, and depression all seem to aggravate the symptoms of tinnitus and worsen the patient’s overall quality of life. [9]
To understand why this occurs, it is important to understand that emotional responses are not exclusive to the limbic system, but can be found to occur in the lower brainstem and autonomic nervous system, one of the regions affected by tinnitus. Emotional responses to stimuli, such as anxiety, can be found to coincide with activation in the lower brainstem regions such as the locus coeruleus. The chain of nerve cluster cells distributed along the brainstem is responsible for producing serotonin, which can cause depression when imbalanced. Serotonin is evidenced to be released into the dorsal cochlear nucleus with exposure to loud noises, which plays heavily on the emotional response of the tinnitus patient. Even if these emotional factors do not cause tinnitus, it should be at least considered that tinnitus is exaggerated by psychopathological symptoms. The life quality of patients at least can be increased by treating these symptoms. [2]
Anesthetic Treaments
One of the more promising treatment comes from lidocaine, a common amino amide local anesthetic which does not merely preventing pain signals from propagating to the brain but stops them before they begin by blocking the fast voltage gated sodium (Na+) channels in the neuronal cell membrane that are responsible for signal propagation. [16] Lidocaine affects the ear by blocking the open sodium channels, with the efficiency of the channel blocking increasing in proportion to the number of channels that are open. As a result, the inhibitory effect of lidocaine accumulates with repetitive stimuli, such as those produced by tinnitus. [17] Lidocaine has been used extensively in testing for tinnitus treatment, in which the lidocaine was administered to the ear through intravenous injection. In some cases, a mixture of lidocaine and bupivocaine, another amino amide anesthetic for uses such as nerve blocking, was used in the research tests. Through audiological and brain imagining studies, the anatomical sites where tinnitus suppression occurs have been located in the cochlea, as well as hair cell membranes in the inner ear. Further, molecular studies were used to elucidate the action of lidocaine on the cellular level. In every test, a high number of patients reported that the tinnitus was completely suppressed after the lidocaine injection. Patients were monitored after the procedure, and results of tinnitus suppression lasted up to four weeks to a month in the best cases. However, in every case the symptoms eventually recurred, as the lidocaine wore off. [17], [18], [19] Increased amounts are not feasible, as lidocaine must be carefully administered so as not to cause toxicity from excess, which can affect the central nervous system and cardiovascular functions. [16]
However, building on the success of lidocaine, research has been conducted to prolong the effects of lidocaine by administering carbamazepine post-treatment of lidocaine. Following the procedure of previous studies, patients were administered intravenous injections of lidocaine into the ear. Following favorable results from the lidocaine, those patients were orally administered carbamazepine and monitored. Afterwards, half of the patients treated with carbamazepine maintained the improvement of tinnitus. [20]
Conclusion
Tinnitus is one of the most troubling hearing conditions of our time, due to both its increasingly widespread presence, effects on the physical, mental, and emotional health of the patient, and the varying underlying causes for it. The difficulties in dealing with a constant, unnerving ring for their rest of their lives can be crippling to most in many ways, and it is of vital importance to give those suffering from this condition the hope that there are treatments to alleviate their suffering and eventually cure their condition, whether that be through natural remedies or drugs or acoustic therapies. Continued encouragement of the treatments being tested, as well counseling and therapy, will give tinnitus patients a strong foundation to stand on and resolve to continue their lives unimpeded.
Because of the multitude of ways that tinnitus can manifest and the varied causes behind it, it is still difficult to pinpoint a cure for tinnitus. It may well be that there is no single cure, and that each case must be handled separately based on the patient’s criteria. However, great strides are being made to gain greater understand of tinnitus and find treatments for each group through the determined efforts those scientists who still battle to find the answers to the many unsolved questions surrounding tinnitus. And as many treatments are being tested, it may well be that the answer that has eluded so many physicians may be uncovered any day. This promising news can mean the difference between the prospect of miserable, life-long companion and the hope for a brighter future. Tinnitus can and will be cured; it is merely a matter of effort and time.
Hurtuk A, Dome C, Holloman CH, Wolfe K, Welling DB, Dodson EE, & Jacob A. Melatonin: can it stop the ringing? The Annals of otology, rhinology, and laryngology: 120 (7), 433-440. http://www.ncbi.nlm.nih.gov/pubmed/21859051
Belli H, Belli S, Oktay MF, Ural C. Psychopathological dimensions of tinnitus and psychopharmacologic approaches in its treatment. General Hospital Psychiatry: 34 (3), 282-289. http://dx.doi.org/10.1016/j.genhosppsych.2011.12.006
Bayar N, Böke B, Turan E, Belgin E. Efficacy of amitriptyline in the treatment of subjective tinnitus. J Otolaryngol: 30 (5), 300-303. http://www.ncbi.nlm.nih.gov/pubmed/11771024
Mihail RC, Crowley JM, Walden BE, Fishburne J, Reinwall JE, Zajtchuk JT. The tricyclic trimipramine in the treatment of subjective tinnitus. Ann Otol Rhinol Laryngol: 97 (2), 120-123. http://www.ncbi.nlm.nih.gov/pubmed/3355041
Trellakis S, Lautermann J, Lehnerdt G. Lidocaine: neurobiological targets and effects on the auditory system. Progress in Brain Research: 166, 303-322 http://dx.doi.org/10.1016/S0079-6123(07)66028-2
Kalcioglu MT, Bayindir T, Erdem T, Ozturan O. Objective evaluation of the effects of intravenous lidocaine on tinnitus. Hearing Research: 199 (1-2), 81-88. http://dx.doi.org/10.1016/j.heares.2004.08.004
Weinmeister KP. Prolonged suppression of tinnitus after peripheral nerve block using bupivacaine and lidocaine. Regional Anesthesia and Pain Medicine: 25 (1), 67-68. http://dx.doi.org/10.1016/S1098-7339(00)80013-9
Sanchez TG, Balbani APS, Bittar RSM, Bento RF, Câmara J. Lidocaine test in patients with tinnitus: rationale of accomplishment and relation to the treatment with carbamazepine. Auris Nasus Larynx: 26 (4), 411-417. http://dx.doi.org/10.1016/S0385-8146(99)00020-6
Chem 367
December 2012
Tinnitus: Causes and Cures
Abstract
This paper will discuss the hearing condition known as tinnitus and examine the drugs and nutrients that could potentially shed light on statistically reliable treatments in the future. First, a short history of the condition itself will be presented, followed by a brief description of each of the chemical treatments that have claimed success in treating or suppressing tinnitus symptoms. Finally, an overview of ways to prevent tinnitus from occurring will be discussed.
Introduction
Tinnitus is the perception of sound, usually a ringing noise, within the human ear in the absence of corresponding external stimuli. It is a fairly common condition, particularly in the age group of 55 and 65 years old. Although a wide range of causes for tinnitus exists, the most common is noise-induced hearing loss. This is particularly problematic in recent times, as many of today’s youth and young adults unknowingly subject themselves to damaging levels of noise, particularly music, through the invention of speakers that amplify noise and headphones that deliver sound directly into the ear canal without any means for the sound to be lowered in decibel level through absorption of the surroundings. These ease with which this condition occurs, along with the difficulty in circumventing the subjective nature of this condition makes it important to discover a full-proof method of treating tinnitus, as well as how to avoid getting it in the first place. [1]
History of Tinnitus
Tinnitus is a condition that can affect the outer, middle, and inner ear of one or both ears. It is the perception of auditory stimuli not produced externally to the ear. The exactly noise perceived can vary in pitch (high to low), tone (single or multi-tonal), and frequency (constant, pulsing, or intermittent). Tinnitus is not a disease or disorder, but a condition that can result from a wide range of underlying causes: neurological damage (such as multiple sclerosis), ear infections, oxidative stress, muscle spasms, wax build-up in the ear canal, sensoineural hearing loss, congenital hearing loss, and exposure to loud sounds. Noise-induced hearing loss is the most common, resulting from excessively loud sounds, firearms, and music. [1]
The condition is rated clinically according to the practical difficulties it imposes on the patient, such as interference with sleep, quiet activities (particularly those that require concentration), and normal daily activities, causing withdrawal or depression. Tinnitus can be classified as objective, where the perceived noise is something produced inside the ear such as muscle spams that is audible to the physician, and subjective, where the noise is audible only to the patient. Subjective tinnitus, the far more common form that accounts for 95% of tinnitus cases, is a symptom that is associated with practically every known ear disorder. [1]
Tinnitus has been eluding health care professionals for quite some time. As a usually subjective phenomenon, it is difficult to measure using objective tests, such as by audiometric test, where the perceived noise is compared with noise of known frequency and intensity. Because tinnitus is subjective, two individuals may demonstrate identical tinnitus loudness and pitch matches yet be affected in significantly different ways. The severity of the tinnitus is largely a function of the individual's reaction to the condition. [1]
Alterations to the balance of excitatory and inhibitory inputs of neurons in the auditory system are believed to cause tinnitus. High-intensity noises that cause hearing loss damage auditory receptions in the inner ear, resulting in hearing loss that alters neuronal activity in the auditory system of the brain, causing tinnitus. Several areas of the brain show signs of tinnitus activity; this is most notable in the dorsal cochlear nucleus where direct input is received from the auditory nerve. Loss of auditory nerve function results in high rates neural activity in the absence of stimuli. The brain then perceives the increased neural activity as sound, particularly high frequency sound such as the ringing perceived by tinnitus patients. The inferior colliculus, which receives input from the cochlear nucleus, increases in spontaneous neural activity as a result. [2], [3] The dorsal nuclear cochlear nucleus is considered the primary source of tinnitus activity, as its role in sound localization and inhibition of noises in hearing, in addition to its ability to be influenced by attentional and emotional impulses sent from the brain, makes it highly compatible with the symptoms resulting from tinnitus. [3]
The auditory cortex is also affected, causing neural impulses to synchronize so that impulses occur simultaneously, amplifying tinnitus. Damage to the ear from noise exposure distorts frequency perception such that the brain becomes insensitive to sound frequencies of the range of hearing loss. Neurons whose input frequency have been lost alter to become sensitive to noises at the edge of the lost frequency, resulting in an expansion of the representation of frequencies near that of the hearing loss at the cost of equal representation of the entire range of audible frequencies. This could possibly affect tinnitus. [2], [3]
Hearing loss throws off the balance between excitatory synapses which increase neural activity and inhibitory synapses that reduce neural activity. Excitation is necessary for delivering responses to stimuli throughout the brain and enhancing important signals, while inhibition is necessary for turning off response to stimuli to avoid an information overload to the brain. Hearing loss results in a decrease of auditory inhibition, coupled with an increase in excitatory synaptic response. Decrease in inhibitory synapses could thus be responsible for the inability of many tinnitus patients to filter out the tinnitus ringing for other sounds. In addition, increased levels of acetylcholine have been noted to occur after hearing loss. This could be the brain’s mechanism to boost its ability to perceiving incoming signals. The resulting amplification allows the neural signals caused by hearing loss to be more easily perceived, thus resulting in tinnitus. [2]
Tinnitus plays on the consciousness of the patient based on the intensity of its frequency, with fairly light tinnitus merely reduced to an annoying background noise while debilitating tinnitus consuming the attention of the patient. It is thought that those whose tinnitus falls into a lower level of consciousness may possess cortical deafness that prevents the person from deciphering or associating sounds despite being able to perceive them, which in turn keeps the tinnitus from rising high enough in the hierarchy of awareness to pose a notable issue. Those with remaining function in the auditory cortex suffer from more acute tinnitus due the piercing quality of the noise, which is perceived by the limbic cortex as a disturbance. This causes a negative association to the sound. [2]
The attention to the noise produced by tinnitus can also be traced back to the dorsal cochlear nucleus, inferior colliculi, and the brainstem, as evidenced by cats’ ability to discern noises of varying intensities arriving at the two ears at different times, which requires attention. Changes in the activity of the dorsal cochlear nucleus in animals when they shift their attention between auditory and non-auditory stimuli suggest the dorsal cochlear nucleus’ role in attention. In addition, it has been shown that the dorsal cochlear nucleus and inferior colliculi function in attention regulation. Testing with hydranencephaly sufferers who lack of cerebral hemispheres but maintain an intact brainstem has shown these individuals to show interest to certain sounds and respond emotionally to them. This suggests that these low-level auditory centers might serve to enable the brain to focus on specific details in the sensory world and while ignoring those deemed irrelevant. [2], [3]
Auditory Treaments
Current research suggests that even though tinnitus may initially be caused by an injury to the ear, ultimately an auditory pattern is established in the brain. Therefore, many treatment approaches are directed at the brain, not the ear. [2], [3] Other treatments reduce or mask the noise, making tinnitus less noticeable. It has been theorized that hearing can be restored by reversing the plasticity changes made by hearing loss through restoration of sound stimulation to the areas of the brain that have lost input. This restored plasticity should reduce activity that causes tinnitus. In a series of studies, cats were exposed to loud noises to induce hearing loss. All the changes to auditory responses in the brain, such as the increases neural plasticity, synaptic changes, and the others detailed above were found to have occurred in the cats. These same cats were then exposed to auditory stimulation in the frequency range of hearing loss and were found to have greatly restored the balance of synapses and reduced the activity of neurons and their synchronization. This greatly supports the idea that acoustic therapies could be a potent treatment for hearing loss and tinnitus symptoms. [2]
Related to audio therapies, many tinnitus victims are encouraged to use white noise therapy. White noise is a combination of all the frequencies of sound, equally distributed across the audio band. Simply put, it is an artificially produced noise that is steady and unvarying in quality and unobtrusive to the listener. This gives it the quality of “background noise” that people tend to find soothing. Tinnitus patients utilize headphones or speakers to transmit the white noise and help to cover up the sound of tinnitus while conditioning the brain to place the tinnitus sounds at a position of lower attention. Although it is generally agreed that white noise therapy is incapable of curing tinnitus, it is quite useful for masking the noise, particularly during sleep where tinnitus is most noticeable. In addition to masking the ringing, white noise therapy has been found to be highly therapeutic for many people. The calming effect is useful for dealing with the emotional and attentional factors that plague many tinnitus patients. [4]
Natural Treaments
The safest and most natural remedies for tinnitus are those that occur within the human body naturally. Melatonin is a naturally occurring chemical compound with a host of uses in the human body, as well as animals and plants. It functions as a regulator in the circadian rhythm, an antioxidant that can easily cross cell membranes and the blood-brain barrier, a participant in the immune system (though the degree to which it serves is thus far unclear), and an anti-aging agent. [5]
Because of its role in the regulation of the circadian rhythm, which includes the sleeping cycle, melatonin has been investigated as a possible alleviation for tinnitus patients with resulting sleep disorders. Multiple sources have tested this by prescribing a certain amount of melatonin to patients and observing their sleep over a period of several weeks. All the studies agreed that there exists an association between the amount of improvement in sleep and tinnitus intensity and the added supplementation of melatonin. The melatonin treatment had the greatest impact among patients with the worst sleep quality, but not necessarily the most severe tinnitus in all studies. Interestingly, most reported that those most affected were men, and whose tinnitus appeared to be the result of exposure to high intensity noises. [5]
Another possible treatment is zinc supplementation. Zinc, an essential trace element present in all organs, tissues, fluids, and secretions of the body, is widely distributed in the central nervous system, including the auditory pathway and the cochlea. Some studies have shown that hypozincemia, a deficiency in zinc, could cause tinnitus in patients with relatively normal hearing or exacerbate tinnitus symptoms in others. From these studies, it has been concluded that clinical and subjective improvement of tinnitus can be achieves by supplementation with oral zinc medication. Although the extent to which zinc supplements are capable of treating tinnitus in the long run has not been studied with large groups, its smaller scale success indicates that it is well worth looking into. [6], [7], [8]
Antidepressant Treaments
There exist more controversial treatments, most revolving around antidepressant drugs. Many physicians prescribe benzodiazepines to patients suffering from tinnitus. Benzodiazepines are a group of drugs that affect brain function to alter perception, mood, cognition, and behavior (psychoactive drugs). It has a host of uses in the medical community for its sedative, hypnotic, anxiolytic, anticonvulsant, and muscle relaxant properties, which are useful in a variety of indications such as alcohol dependence, seizures, anxiety, panic, agitation and insomnia. In some cases, it has been said to help alleviate the symptoms of tinnitus, as well as the depression that often accompanies it. [9] However, benzodiazepines carry a stigma for their host of adverse affects, particularly their withdrawal and long term effects that can cause physical and mental deterioration in the patient. Tricyclics, a wide variety of drugs that can function as antidepressants, antipsychotics, or antihistamines have shown some capacity to treat tinnitus, usually where depression is involved. Amitroptyline has been shown to provide some relief for tinnitus, particularly in those whose tinnitus is exacerbated by emotional states. [10] In some studies to have a high percentage rate of success among those suffering from tinnitus, as high as 95%. [11] However, in many other studies, the results are far less enthusiastic. In some cases, the success rate with the amitroptyline was roughly equivalent to the placebo group and thus insignificant in treating the tinnitus; in others, the effects grew worse with increased amount of the tricyclic. [12], [13]
However, one drug that has shown potential is acamprosate, a drug that stabilizes the chemical balance of the brain. This is usually used to treat alcohol dependence, but has shown promising capacity for treating tinnitus and carries far fewer and less acute symptoms than benzodiazepines or tricyclics. It is believed that acamprosate may improve tinnitus by acting on the ear and the nervous system by means of glutamate antagonist and GABA agonist action. [14] In the studies performed it had a very high rate of success in relieving tinnitus symptoms, with many patients claiming that it had relieved tinnitus up to 50%. In all, acamprosate has been considered a safe and alternative treatment for tinnitus, particularly of sensorineural origin. [14], [15]
Although the disadvantages of drug like antidepressants may make their suitability as tinnitus treatments suspect, the questions that have arisen from the studies involved with these drugs have brought a new angle on tinnitus to light. The nature of tinnitus may be such that much of its effects are rooted deep in the mind. Factors like stress, blood pressure, and depression all seem to aggravate the symptoms of tinnitus and worsen the patient’s overall quality of life. [9]
To understand why this occurs, it is important to understand that emotional responses are not exclusive to the limbic system, but can be found to occur in the lower brainstem and autonomic nervous system, one of the regions affected by tinnitus. Emotional responses to stimuli, such as anxiety, can be found to coincide with activation in the lower brainstem regions such as the locus coeruleus. The chain of nerve cluster cells distributed along the brainstem is responsible for producing serotonin, which can cause depression when imbalanced. Serotonin is evidenced to be released into the dorsal cochlear nucleus with exposure to loud noises, which plays heavily on the emotional response of the tinnitus patient. Even if these emotional factors do not cause tinnitus, it should be at least considered that tinnitus is exaggerated by psychopathological symptoms. The life quality of patients at least can be increased by treating these symptoms. [2]
Anesthetic Treaments
One of the more promising treatment comes from lidocaine, a common amino amide local anesthetic which does not merely preventing pain signals from propagating to the brain but stops them before they begin by blocking the fast voltage gated sodium (Na+) channels in the neuronal cell membrane that are responsible for signal propagation. [16] Lidocaine affects the ear by blocking the open sodium channels, with the efficiency of the channel blocking increasing in proportion to the number of channels that are open. As a result, the inhibitory effect of lidocaine accumulates with repetitive stimuli, such as those produced by tinnitus. [17] Lidocaine has been used extensively in testing for tinnitus treatment, in which the lidocaine was administered to the ear through intravenous injection. In some cases, a mixture of lidocaine and bupivocaine, another amino amide anesthetic for uses such as nerve blocking, was used in the research tests. Through audiological and brain imagining studies, the anatomical sites where tinnitus suppression occurs have been located in the cochlea, as well as hair cell membranes in the inner ear. Further, molecular studies were used to elucidate the action of lidocaine on the cellular level. In every test, a high number of patients reported that the tinnitus was completely suppressed after the lidocaine injection. Patients were monitored after the procedure, and results of tinnitus suppression lasted up to four weeks to a month in the best cases. However, in every case the symptoms eventually recurred, as the lidocaine wore off. [17], [18], [19] Increased amounts are not feasible, as lidocaine must be carefully administered so as not to cause toxicity from excess, which can affect the central nervous system and cardiovascular functions. [16]
However, building on the success of lidocaine, research has been conducted to prolong the effects of lidocaine by administering carbamazepine post-treatment of lidocaine. Following the procedure of previous studies, patients were administered intravenous injections of lidocaine into the ear. Following favorable results from the lidocaine, those patients were orally administered carbamazepine and monitored. Afterwards, half of the patients treated with carbamazepine maintained the improvement of tinnitus. [20]
Conclusion
Tinnitus is one of the most troubling hearing conditions of our time, due to both its increasingly widespread presence, effects on the physical, mental, and emotional health of the patient, and the varying underlying causes for it. The difficulties in dealing with a constant, unnerving ring for their rest of their lives can be crippling to most in many ways, and it is of vital importance to give those suffering from this condition the hope that there are treatments to alleviate their suffering and eventually cure their condition, whether that be through natural remedies or drugs or acoustic therapies. Continued encouragement of the treatments being tested, as well counseling and therapy, will give tinnitus patients a strong foundation to stand on and resolve to continue their lives unimpeded.
Because of the multitude of ways that tinnitus can manifest and the varied causes behind it, it is still difficult to pinpoint a cure for tinnitus. It may well be that there is no single cure, and that each case must be handled separately based on the patient’s criteria. However, great strides are being made to gain greater understand of tinnitus and find treatments for each group through the determined efforts those scientists who still battle to find the answers to the many unsolved questions surrounding tinnitus. And as many treatments are being tested, it may well be that the answer that has eluded so many physicians may be uncovered any day. This promising news can mean the difference between the prospect of miserable, life-long companion and the hope for a brighter future. Tinnitus can and will be cured; it is merely a matter of effort and time.
References
http://dx.doi.org.ezproxy2.library.drexel.edu/10.1016/S0385-8146(97)10004-9